Search

The aim of this study is to determine potential sources and concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in surface soils devoted to different land uses in northwest Algeria. Microwave-assisted extraction (MAE) and gas chromatography/mass spectrometry (GC–MS) methods were applied to quantify 16 PAHs and 7 PCB congeners in surface soils. The sum of the 16 US-EPA priority PAHs and the 7 European indicator PCBs ranged from 133.7 to 2068.0 ng g−1 and from n.d. to 19.34 ng g−1, respectively. PAHs with four to six fused rings were predominant in soils, and their concentrations ranged from 110.1 to 1768.0 ng g−1. Principal component analysis (PCA) and isomeric ratios showed that pyrogenic processes and petrogenic contributions were the main sources of PAHs, while commercial mixtures of PCBs (Aroclor 1254 and 1260) were sources of PCBs in urban/residential and industrial sites. This is a first screening of data about PAHs and PCBs in soils around a Mediterranean city (Oran, North Africa), and a first step toward a better understanding of the impact of anthropogenic activities on land uses. [ABSTRACT FROM AUTHOR]

Azo dyes make up a major class of dyes that have been widely studied for their diverse applications. In this study, we successfully applied nano-γ-Fe 2 O 3 /TiO 2 as a nanocatalyst to improve the photodegradation efficiency of azo dyes (Orange G (OG) dye as a model) from aqueous solution under white light-emitting diode (LED) irradiation. We also investigated the degradation mechanisms and pathways of OG dye as well as the effects of the initial pH value, amount of H 2 O 2 , catalyst dosage, and dye concentration on the degradation processes. The characterizations of nano-γ-Fe 2 O 3 and γ-Fe 2 O 3 Nps/TiO 2 were carried out using various techniques, including X-ray diffractometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and UV-visible spectroscopy. The efficiency of the photodegradation reaction of OG was found to follow pseudo-first-order kinetics (Langmuir-Hinshelwood model) with a rate constant of 0.0338 min -1 and an R 2 of 0.9906. Scavenger experiments revealed that hydroxyl radicals and superoxide anion radicals were the dominant species in the OG photocatalytic oxidation mechanism. This work provides a new method for designing highly efficient heterostructure-based photocatalysts (γ-Fe 2 O 3 Nps/TiO 2 ) based on LED light irradiation for environmental applications., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)